Guns can hit tacs at 100 yards quite regularly if you got the right combinations. Top grade barrel, trigger 2o/z, bedded, scopewith 1/4" dot and A/O my brother has a 223 Rem 700 action with a 26" Hart Premium stainless andit is a true constant -.250 gun and he can hit tacks with it.
I had a Rem 700 made up by Hart Barrels added, jewell, tubbs pin it will do it but its not fun to shoot 7mmwsm lots of recoil
If you want to see what a 1000yard gun can do take a look;
www.6mmbr.com/gunweek050.htmlthis group is amazing at 1000 yards